Our research objectives address several aspects of retinoid and protein metabolism in ocular tissues. We wish to understand how retinoids are delivered to and taken up by cephalopod photoreceptors and rabbit lacrimal gland cells. We are also interested in the synthesis of specific proteins during photoreceptor development, and in opsin transport by photoreceptors. Our proposed objectives include pilot studies and experiments to expand and complete existing research investigations. Our objectives specifically address the following issues. 1. Retinoid transport in cephalopod blood. HPLC methods will be used to detect retinol in octopus blood and to identify proteins involved in retinoid transport. 2. SRBP-like receptors in the cephalopod retina. Retinoid must be delivered to the photoreceptors for rhodopsin and retinochrome biosynthesis. EM methods will be used to detect the presence and location of receptors for a serum retinol-binding like protein in octopus photoreceptors. 3. Photoreceptor development. EM methods will be used to study rhabdom, myeloid body, and interphotoreceptor matrix formation in developing octopus retinas. Immunocytochemistry will allow us to determine when photopigments and retinal binding protein are first synthesized and to coordinate the synthesis of these proteins with the formation of the cellular organelles and compartments of which they are a part. 4. EM localization of SRBP receptors in the rabbit lacrimal gland. We will precisely localize SRBP receptors on lacrimal gland cells. Our methods may detect endocytotic mechanisms in the uptake of retinoid. 5. Opsin transport in photoreceptors. We will continue past MBRS investigations to determine if newly synthesized opsin is transported by coated vesicles. Anti-clathrin will be purified and used in double label immunocytochemical experiments to identify putative opsin-containing coated vesicles. The biomedical research skills of our MBRS students will be developed. The students will be exposed to state-of-the-art techniques in cell biology and will be involved in every scientific aspect of the proposed research. They will attend meetings and be co-authors on resulting publications. We will strongly encourage them to pursue biomedical research careers after graduation.